Portable CombustionAnalyzers

ASGE ConferenceLas Vegas, NVJune 3, 2014

Agenda

• General Theory

• Understanding Emissions

• Understanding Electrochemical Sensors

• Understanding Sample Conditioning

• Proper Testing Procedures

• Data Collection

General TheoryGeneral Theory

What do portable combustion analyzers do?

Measure exhaust gases that are formed as a result of combustion.

Why use portable combustion analyzers?

Measuring the exhaust gases allows you to tune your equipment for combustion

efficiency, decreasing fuel consumption and thus decreasing emissions.

What type of analyzer is right for my application?

Analyzers range from small handheld units for basic tuning to larger multi-gas

analyzers for compliance-level emissions testing. Determining which type of

analyzer best fits your needs depends on the fuel type and size of your equipment,

along with the application (e.g. spot-checking, installation, production line, etc.)

Portable Analyzer Features

• Probe & Sample Line

• Water Removal System

• Internal Pump

• Electrochemical Sensors

• Display Screen

These are the core features of any

portable combustion analyzer.

However, there are important

differences in quality and reliability

among analyzer brands.

Portable Analyzer Features (cont)

Optional features include:

•Printer

•Heated sample line (increases NO2

and SO2 accuracy)

•USB, Bluetooth, or WiFi

•Remote display

•Software

•Calibration gases

For data collection, the printer is the

easiest way to collect results. To

create data reports, you will need

software and some way of

communicating to a computer.

Portable Analyzer Brands

• ECOM

• Bacharach

• Testo

• Enerac

• E-Instruments

• UEI

• Kane Maye

Understanding EmissionsUnderstanding Emissions

Air consists of:

78% nitrogen (N2) and 20.9% oxygen (O2)

Fuel consists of:

molecular chains of hydrogen (H2) and carbon (C)generically called hydrocarbons

Fuel + air + ignition = combustion

Emission Formation

Emission Formation

Ideal combustion, i.e. stoichiometric combustion, chemical formula

C + H + O2 + N2 → CO2 + H2O + N2 (heat)

C + 4H + 2O2 + N2 → CO2 + 2H2O + N2 (heat) *BALANCED*

Combustion is never perfect!

Fuel + air → CO2 + H2O + heat (energy) + byproducts

A complete combustion is a process burning all the carbon to CO2 & all thehydrogen to H2O

Fuel + air → CO2 + H2O + heat (energy)

CO, CO2, NO, NO2, (NOx), SO2, O2, & HC

By-Products of Combustion

As N2, O2, CxHy and other componentsare oxidized (burned), different chemicalcompounds are formed:

O2, CO, NO, NO2

CO2 Formation

Indirectly proportional to O2 formation- As O2 goes up, CO2 goes down

Analyzer calculates CO2, which is accurate if:- The O2 % is correct- The correct fuel type is selected in the analyzer

CO Formation

High CO indicates unburnt fuel “Too rich” CO is troublesome for some electrochemical

analyzers to measure:- Accurate measurement of CO requires a

potassium permanganate filter to scrub outNO2 & SO2 which may interfere with thereaction at the sensor

NOx Formation

NOx = NO + NO2 Nitrous oxides Higher combustion temp = Higher NOx formation Usually, as CO goes up, NOx goes down

- And vice versa In the stack, NOx is primarily NO, but in the

atmosphere all NO converts to NO2- This is why it is collectively termed “NOx”

Understanding

Electrochemical Sensors

Understanding

Electrochemical Sensors

Electrochemical Sensor Technology

A small capillary allows gas to diffuse intothe sensor at controlled rate

A chemical reaction occurs:oxidation or reduction

The chemical reaction generates a current.

This current is directly proportional to theconcentration of the gas.

• How often do I need to calibrate?• This depends on 2 main factors: the ppm levels of your gas

samples and the frequency of testing. It is highly recommended tohave your own calibration gas to perform periodic “bump checks”between annual factory calibrations.

• What concentration of calibration gas should I get?• You will want to get a calibration gas that is at the high range of the

gases you expect to see.

• How does calibration work?• Calibration of electrochemical sensors are plotted along a linear

curve. This means you need a good zero point and a goodcalibration point to get an accurate calibration curve across theentire range of the sensor.

Calibration

Understanding Sample

Conditioning

Understanding Sample

Conditioning

• Sample conditioning = transforming a hot, wet, dirty gas into acool, dry, clean gas without compromising accuracy

• Sample conditioning system is comprised of:• Pump• Filters• Water removal

• Higher speed pumps increase accuracy by decreasing the chancethat water will form in the sample line

• If water forms in the sample line, water-soluble gases (NO2 +SO2) will drop out by binding to water

• Using a heated sample line is the most accurate way to measureNOx and SO2

Sample Conditioning

Gas Cooler & Moisture Removal

Water Removal

Condensate filter < Ambient dispersive cooler < Peltier thermoelectric cooler

filtersNOx/SOx filter(potassium permanganate)

Particulate filter

In-line smoke filter

Filtration

• The CO sensor is the most susceptible to over-saturation. Exposing the COsensor to a very high concentration of CO can “kill” the sensor.

• A CO purge pump introduces fresh air into the CO sensor when COconcentrations exceed pre-set limits of the sensor (usually 4000ppm).

• This protects the CO sensor from over-range damage.

• The analyzer will monitor the CO level and turn the purge pump off when levelsdrop below the maximum range of the sensors.

• Since the CO gas path is independent of the other sensors, you will be able tosee all the other readings and tune the combustion accordingly.

CO Purge Pump

Proper Testing ProceduresProper Testing Procedures

1. Start the analyzer in fresh air.

2. Insert probe into gas stream and wait 2 minutes (wait up to 5minutes if you have a lower speed pump).

3. Observe the readings on the display.

4. Remove sample line and allow analyzer to purge with fresh air untilO2 readings are above 20.0% and other readings are below 15 ppmbefore powering off.

Taking a Snapshot

1. Start the analyzer in fresh air.

2. Allow the analyzer to run for 10-20 minutes to reach a stabletemperature.

3. Turn off analyzer and re-power. This resets the temperaturecompensation to the current internal temperature.

4. Insert probe into gas stream and wait 2 minutes (wait up to 5minutes if you have a lower speed pump).

5. Observe the readings on the display.

6. Remove sample line and allow analyzer to purge with fresh airuntil O2 readings are above 20.0% and other readings are below15 ppm before powering off.

Testing Over Time

ASTM D6522 Test Protocol

Find the correct sampling port Sample within a straight portion of the stack, avoiding any bends in the stream which

may affect the ‘core exhaust stream’ Position the tip of the probe in the center of the stack

Reporting requirements Sensor temperature (internal temperature) Pump flow rate O2, CO, NO, NO2 (NOx) readings

Pre-test calibration

• Calibrate the CO, NO, & NO2sensors prior to the test

Emission test

• 3 test runs at 20 minutes each• -Ramp-up

-Measure-Purge(Repeat 2x)

Post-test check

• Apply calibration gas to the CO,NO, & NO2 sensors after the test

• Can’t drift more than 5% for CO,NO, & NO2 and 0.5% for O2

Data CollectionData Collection

Data Collection Options

1. Printer

2. On board data logging

3. SD memory card-Log data on board, then transfer to computer later

4. USB connection-Hard wire connection to computer

5. Bluetooth connection-Wireless connection to computer

6. WiFi connection-Wireless connection to computer & smart phone

7. Analogue outputs

WiFi and Smart Phone AppsWiFi and Smart Phone Apps

Thank you

1628 Oakbrook DriveGainesville, GA 30507

Telephone: 770.532.3280Fax: 770.532.3620www.ecomusa.com